Cutting speeds of different size chains, .325 vs. 3/8

[memory]

We all know including me that 3/8 chain cuts faster than .325 if you have a saw big enough. But why is that? You take the same saw that can run a 3/8 chain with authority and put a .325 chain on there, why would that not cut faster? With the .325, you are cutting less wood so why wouldn't you cut faster?

Also, my cousin has a Husky 460 Rancher currently running a 20" bar with .325 chain. Would he be able to use 3/8 chain on that saw?

Sorry if this has already been asked before.

 

[Guido Salvage]

In theory you can run any chain on a saw as long as you can find a rim/sprocket to match the pitch and a bar with the proper gauge.

 

[SawTroll]

In theory you can run any chain on a saw as long as you can find a rim/sprocket to match the pitch and a bar with the proper gauge.

It is for a large part about the "gearing" that is a result of different size drive sprockets. As a rule of thumb, saws that are faster with .325x7 than with .325x8 often will be faster with .325x7 than with 3/8x7 as well. Saws that are faster with .325x8 than with .325x7 may be even faster with 3/8x7, but that doesn't always happen. The exact chain model is a major factor.

The only way to really know is to try the options in the wood in question, as there are a lot of variables.

 

[Philbert]

We all know including me that 3/8 chain cuts faster than .325 if you have a saw big enough.

3/8 is generally going to take a bigger chunk/chip of wood than a .325 chain, all things equal. The cutters are physically larger. At the same chain speed, the .325 will take more of the smaller chips than the 3/8 chain. If you could measure the chip size you could calculate the volume of wood removed per rotation of each chain.

You comments on power are right on - too large of a chain may bog the chain down a bit, versus keeping the saw cutting at higher RPMs. Saw Troll's comments on rim size note how that can affect the speed of the chain and torque, which may be a noticeable factor in certain types of wood. Bottom line is that the chain needs to be matched to the saw and the work if you are looking to optimize the cutting speed.

Philbert

 

[SawTroll]

One of many factors is that a .325 chain will put on average about 10% more cutters in the wood.

Some times it also is a factor that there are many more "sub-standard" chain designs on the market in .325 than in 3/8 (regular 3/8" that is, not the lo-pro variety). .325 on saws with decent power mainly is about Oregon LP/LPX (best) and Stihl RSC/RS (a close second).

 

[MPE]

Speed isn't the only consideration. Chip clearance and smoothness of the cut is also something to consider. In smaller stuff, brushing and pruning and small trees/fence rows, .325" is usually smoother which means safer which also means you're more productive. In bigger wood, assuming the saw can pull it, 3/8" seems more productive to me, especially on longer bars, where .325" seems to have a harder time keeping chips cleared out.

 

[Abflyboy]

I played with .325 vs 3/8" chain on both my 028WB and 026 PRO saws. Both port jobs are nearly identical.

The 028 prefers .325" very much and tends to bog in anything with 3/8" chain pitch. It has plenty more smash than before porting but is not a rocket.

My 026 turned out to be a screamer when it was all done, is way faster with 3/8" and pulls it with authority.

I figured the end result with chain pitch would be the opposite since the 028 has what feels like more 'grunt' and the 026 is a revver.

Just my $.02 if it's worth even that. Not an expert but I like trying different things with my chains, bars, and rim sprockets.

Like mentioned above, you just gotta try it and see if it's good or not. Depth of rakers can influence cutting performance, full chisel vs semi chisel in .325" can also affect cutting speed.

 

[SawTroll]

...

Like mentioned above, you just gotta try it and see if it's good or not. Depth of rakers can influence cutting performance, full chisel vs semi chisel in .325" can also affect cutting speed.

Yes, there are a lot of factors involved. For the rakers, I mostly use the "soft" setting of the Husky guides, which result in a .030 setting on new chain, and more on a used one. It is progressive, as any raker guide should be (but many aren't).

 

[HuskStihl]

It the rakers are adjusted equally, a .325 cutter should remove a chip which is just as deep, only narrower than a .375 cutter. As Philbert said, that would result in a lower volume of wood being removed cut. That should translate into a lower power requirement allowing higher "gearing" (bigger sprocket) and more speed. A single cutter of .325 should be acutally faster than a 3/8 cutter with the same raker depth, not slower for any given saw, given a properly matched sprocket to the task. This is all fine to think about, but in the real world, there are lots of cutters in a row gathering chips which will impede the ability of the next cutter to do it's job, thus the need for skip-chain in some situations. I would assume that .325, which has more cutters per given length would be more prone to clogging issues, and that there would be some bar length at which the speed advantage would switch from .325 to 3/8. This is hurting my head, does anybody know if there is any actual available research on this subject which is available to the public? I would assume the chain companies put R&D money into figuring out just this kind of stuff. Sorry to be dense

 

[rupedoggy]

At the end of the day use the chain that you want to. Keep it very sharp with the correct cutting angles and raker settings. Make each tooth the same for both sides and you will cut with maximum efficency. If you really want the fastest, use square ground, square filed chain (not round).

 

[SawTroll]

It the rakers are adjusted equally, a .325 cutter should remove a chip which is just as deep, only narrower than a .375 cutter. As Philbert said, that would result in a lower volume of wood being removed cut. That should translate into a lower power requirement allowing higher "gearing" (bigger sprocket) and more speed. A single cutter of .325 should be acutally faster than a 3/8 cutter with the same raker depth, not slower for any given saw, given a properly matched sprocket to the task. This is all fine to think about, but in the real world, there are lots of cutters in a row gathering chips which will impede the ability of the next cutter to do it's job, thus the need for skip-chain in some situations. I would assume that .325, which has more cutters per given length would be more prone to clogging issues, and that there would be some bar length at which the speed advantage would switch from .325 to 3/8. This is hurting my head, does anybody know if there is any actual available research on this subject which is available to the public? I would assume the chain companies put R&D money into figuring out just this kind of stuff. Sorry to be dense

Yes, a lot of good thinking there - but at some point the higher "gearing" of 3/8x7 vs. .325x7 also will take its toll, so it is hard to say what the end result will be, without actually comparing the options (as usual).

There surely is some "skip" effect by using 3/8", but it only is about 10%.

 

[chugbug]

Was talking to Madsens the other day (if you haven't looked there site over your missing some good info and tutorials ) and I asked the question about running 3/8 chain on a husky 346 xp that comes factory with only .325 and he said they don't like doing it and that husqvarna doesn't advise it ,all he could offer was the possibility of extra load on bearings and over heating issues . And in the end could there be much difference and I'm sure husky did some testing on the matter .

Madsens link- click on saw tuning and repair alot of good stuff Welcome To Madsen's Online

 

[echoshawn]

Yes, there are a lot of factors involved. For the rakers, I mostly use the "soft" setting of the Husky guides, which result in a .030 setting on new chain, and more on a used one. It is progressive, as any raker guide should be (but many aren't).

first of all, I'm surprised a 460 is running .325. Must've been converted from 3/8.

I agree with SawTroll on the Husky guide. Easy to use and consistent. Mine are always filed on the soft setting as well, then again, all I cut is softwoods.

I would recommend 3/8 personally just from my experience. Maybe start with the rakers in the "hard" cutting depth and see how it performs. you can always lower them to the "soft" setting if you think the saw will pull it OK.

3/8 will definitely move more wood faster, but I have seen guys go with too much chain and end up slower in the cut because they had to hold the saw back.

You could always go 3/8 skip too if full comp seems like too much for the saw.

 

[SawTroll]

Was talking to Madsens the other day (if you haven't looked there site over your missing some good info and tutorials ) and I asked the question about running 3/8 chain on a husky 346 xp that comes factory with only .325 and he said they don't like doing it and that husqvarna doesn't advise it ,all he could offer was the possibility of extra load on bearings and over heating issues . And in the end could there be much difference and I'm sure husky did some testing on the matter .

Madsens link- click on saw tuning and repair alot of good stuff Welcome To Madsen's Online

Lots of good info on that site, but they mistakenly assume that 3/8" chain actually is .375, which is pretty far from the truth (it is .366 or .367).

 

[echoshawn]

Lots of good info on that site, but they mistakenly assume that 3/8" chain actually is .375, which is pretty far from the truth (it is .366 or .367).

No offense, but by my math 3 divided by 8 (3/8) is .375.

 

[SawTroll]

No offense, but by my math 3 divided by 8 (3/8) is .375.

Yes, but 3/8" chain doesn't have exactly a 3/8" pitch - it is just a "name". :biggrin:

 

[HuskStihl]

I think this means they just made a change in the Matrix, heads up, Agents may be coming.....

 

[SawTroll]

I think this means they just made a change in the Matrix, heads up, Agents may be coming.....

Madsens should do just that, as it is misleading as it is. :msp_wink:

This is hardly news, it has been known for years on here.....

 

[H 2 H]

I have two 026 both rebuilt in the last 6 months one runs a .325 set-up and the other runs 3/8's setup

The 3/8's b/c cuts faster than the .325 b/c and easier; I switch between the two saws and the 3/8's cuts faster you can feel it while cutting on each saw

I like running the .325 when limbing and the 3/8's on limbs bigger than 6"

One of my 026 isn't broken in yet so we will see more testing this summer like I did for 3/8 chain for my bigger saws; I do have several different chains (brands and types) for both .325 just like I do for 3/8

 

[Rudolf73]

I also depends on the cutter profile and how the chain is set up, raker height, etc. I know some chainsaw racers prefer to run .325 so I am sure they have a good reason for that... Like Sawtroll said, you have more cutters in the wood at anyone time so you can use that to your advantage.